1. Field of the invention
The present invention relates to a power amplifier, and more particularly, to a power amplifier with more advanced linear characteristics.
2. Related Art
In various wireless communication systems, a wireless apparatus represented by user equipment, a base station, or the like, includes an amplifier. Research into the power amplifier that is an important barometer in the wireless communication system has been continued so as to improve a gain of output power, linearity and efficiency of output power, or the like. As a result, the power amplifier needs to satisfy high frequency conditions and high output conditions with the improved material characteristics of devices such as gallium arsenide (GaAs), gallium nitride (GaN) field effect transistor (FET), or the like.
The amplifier included in the wireless apparatus is an apparatus that amplifies and transmits a radio frequency (RF) signal to be transmitted. The amplifier may be set to ensure a pre-determined gain value, amplify the signal by the gain value and transmit the amplified signal when receiving the signal. The amplifier may be considered as having linearity in a specific frequency band, but may have non-linearity by losing the linear characteristics according to the size of the input signal or the frequency band of the input signal. When the amplifier has non-linearity, it is difficult for the wireless apparatus to normally transmit the RF signal to be transmitted and a receiver is difficult to receive and analyze the corresponding RF signal and thus, difficult to perform normal communication. Therefore, a need exists for an apparatus and a method for changing non-linearity of the amplifier into linearity, in connection with the characteristics of the amplifier included in the wireless apparatus.